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Biology of Reproduction 65, 66-71 (2001)
© 2001 Society for the Study of Reproduction, Inc.

Regular Article

Inhibitory Action of Leptin on Early Follicular Growth Differs in Immature and Adult Female Mice

Nobumasa Kikuchia, Kazumichi Andoha, Yumiko Abea, Kiyohiko Yamadaa, Hideki Mizunuma1,a, and Yoshito Ibukia

a Department of Obstetrics and Gynecology, Gunma University School of Medicine, Maebashi, Gunma 371-8511, Japan

ABSTRACT

In order to investigate the action of leptin on early follicular growth, preantral follicles, 95–115 µm in diameter were mechanically isolated from the ovaries of BDF1 hybrid immature (11-day-old) and adult (8-wk-old) mice, and cultured for 4 days in vitro. Follicular growth was assessed by daily changes in follicular diameter and by the amount of estradiol and immunoreactive (IR)-inhibin released into the culture medium at Day 4. Preantral follicles from immature mice showed a significant development in follicular growth as a result of stimulation by GH (1 mIU/ml), insulin-like growth factor (IGF)-I (100 ng/ml) + FSH (100 mIU/ml), and GH (1 mIU/ml) + FSH (100 mIU/ml). Although leptin at concentrations of 1–1000 ng/ml did not have any significant effect on follicular growth stimulated by IGF-I or GH, it significantly inhibited follicular growth in a dose-related manner when follicles were stimulated by IGF-I + FSH and GH + FSH, respectively, suggesting that leptin attenuated the additive effect of FSH. On the other hand, preantral follicles from adult mice were cultured in the presence of FSH, and FSH-dependent follicular growth was inhibited by leptin in a dose-related manner. Because FSH stimulates cAMP production, we investigated the involvement of cAMP in the inhibitory mechanisms of leptin. Preantral follicles from immature and adult mice were cultured in the presence of either 8-Br-cAMP or forskolin. Both 8-Br-cAMP and forskolin significantly increased follicular diameter and hormone secretion in both immature and adult mice. However, 8-Br-cAMP and forskolin-stimulated follicle growth and hormone secretion were significantly inhibited in immature mice by coadministration of leptin, whereas growth of preantral follicles from adult mice was not inhibited by addition of leptin to cultures. These results indicate that leptin causes an inhibitory effect on the early follicular development of both immature and adult mice, but the inhibitory mechanisms of leptin are different.

follicle, follicular development, granulosa cells, growth factors, leptin

INTRODUCTION

Leptin, a recently discovered hormone of the obese gene, is a plasma protein that parallels the amount of fat stores [1–3] and is thought to regulate satiety and energy balance [4]. Because administration of leptin to congenital leptin-deficient obese (ob/ob) mice caused decreased food intake, body weight loss, increased ovarian weight, increased number of follicles, and restoration of fertility [5–9], involvement of leptin in ovarian function has been postulated. Indeed it is shown that ovaries express leptin receptor mRNA [10, 11] and the administration of leptin antagonizes ovarian hormone secretion [12]. An in vitro study using a granulosa cell culture system has shown that leptin impaired estradiol (E2) secretion as a result of stimulation by insulin-like growth factor (IGF)-I [13, 14] and insulin in the presence of FSH [15, 16], suggesting that leptin elicits an inhibitory action on steroid synthesis from granulosa cells. This novel function of leptin on ovarian function may partially account for mechanisms that impair follicular growth in obese women with polycystic ovarian disease (PCOD) [17–21]. However, it is unknown whether leptin suppression of folliculogenesis reflects functional and/or morphological changes up to ovulation. We have shown that preantral follicles from immature mice do not respond to FSH [22], while those from adult mice show a significant growth as a result of stimulation by FSH and that activin A stimulates the growth of preantral follicles from immature mice but suppresses the growth of preantral follicles from adult mice. These results indicate that the nature of preantral follicles in immature and adult mice is different [22]. Because serum leptin concentrations increase in proportion to age and fat volume, it is of interest to investigate the effect of leptin on follicular growth of preantral follicles from immature and adult mice in conjunction with GH, IGF-I, and FSH. The present study was aimed at clarifying the effect of leptin on follicular growth at early stages in immature and adult mice using an in vitro follicular culture system.

MATERIALS AND METHODS

Chemicals

Recombinant murine leptin was obtained from Pepro Tech Inc. (London, UK). 8-Bromoadenosine 3:5-cyclic monophosphate (cAMP) was obtained from Sigma Chemical Co. (St. Louis, MO). Recombinant human (rh)FSH was obtained from Organon (Oss, Netherland). Recombinant human IGF-I was obtained from Sigma and rhGH was provided by Serono Laboratories Co. (Geneva, Switzerland). All other chemicals were of analytical grade or the highest quality commercially available.

Animals

Female BDF1 hybrid mice were purchased from Japan Charles River Inc. (Tokyo, Japan) and housed in a temperature and light-controlled room with a 14L:10D photoperiod. All experiments were carried out in accordance with the principles of The Animal Care and Experimentation Committee, Gunma University, Showa Campus. Food and water were given ad libitum. Eleven-day-old mice and 8-wk-old female mice were killed for the experiments.

Follicle Culture

Preantral follicle culture was prepared as described previously [22, 23]. Ovaries were removed aseptically from 11-day-old and 8-wk-old female mice and placed in 30-mm-diameter Falcon plastic Petri dishes (Falcon, Lincoln, NJ) filled with Dulbecco modified Eagle medium (DMEM; Gibco BRL, Tokyo, Japan). After removing surrounding tissue, ovaries were microdissected under the inverted microscope using 27-gauge needles attached to 1-ml syringes. Approximately 10–15 preantral follicles were mechanically isolated from one ovary in a humidified chamber with 5% CO2 in air at 37°C. Preantral follicles, 95–115 mm in diameter with one or two layers of granulosa cells around the oocyte and an intact basal lamina with theca cells, were used for the experiments. Ten preantral follicles were transferred into a Falcon plastic Petri dish filled with 1 ml serum-free DMEM supplemented with 6.25 µg/ml of insulin, 6.25 µg/ml of transferrin, 6.25 ng/ml of selenious acid, 5.35 µg/ml of linoleic acid, 0.15% BSA, 15 mM Hepes, 45 µg/ml of penicillin G, 350 µg/ml of streptomycin, and 1.75 µg/ml of amphotericin B and cultured in a humidified chamber with 5% CO2 in air at 37°C for 4 days. Ten follicles were cultured in the same dish. Hormones were added at Day 0 at the indicated concentrations and combinations. We could collect 40–60 small preantral follicles from immature mice and 20–30 from adult mice, respectively. Experiments were repeated five to eight times for each reagent.

Histological Evaluation of the Culture Follicles

Follicles were cultured on 30-mm-diameter Falcon plastic petri dishes filled with the culture medium for 4 days. The follicles were fixed with 10% buffered formaldehyde for 24 h at room temperature. The tissues were then embedded in paraffin, sectioned in 3-µm sections, and stained with hematoxylin and eosin. Number of granulosa cells was counted on the section with maximal diameter of oocyte.

Measurements and Statistics

Two-dimensional maximum and minimum lengths of each follicle including an intact basal lamina with theca cells were measured daily by inverted microscope (Olympus IMT-2; Olympus Co., Tokyo, Japan). The mean diameter of the follicle was expressed as the mean of the two lengths. Immunoreactive (IR)-inhibin concentration was measured by double-antibody RIA using rabbit antiserum against bovine follicular fluid inhibin as described previously [24]. The concentrations of E2 were determined by direct RIA using antiestradiol antiserum kindly supplied by Dr. W.F. Crowley, Jr. [25], and radioactive tracers of estradiol-6-(O-carboxymethyl) oximino-(2-[125I]iodohistamine) (Amersham, Buckinghamshire, England). The intraassay coefficients of variation of inhibin and E2 RIA were 2.8% and 2.6% (n = 5), and interassay coefficients of variation of inhibin and E2 RIA were 4.7% and 4.8% (n = 5), respectively. Results were expressed as mean ± SEM. Differences between the means of follicular diameters, hormone levels, and the number of granulosa cells were analyzed by one-way ANOVA followed by Scheffe multiple comparison test. P < 0.05 was considered as significant.

RESULTS

Morphological changes in preantral follicles of immature mice cultured for 4 days in the presence of rhFSH + IGF and rhFSH + GH with or without 30 ng/ml of leptin are shown in Figures 1 and 2. Administration of either of IGF-I (100 mIU/ml) or GH (1 mIU/ml) with 100 mIU/ml of rhFSH significantly increased the number of granulosa cells (Figs. 1, B and D; and 2, B and D, respectively) and the size of follicles (Fig. 3). However, these stimulatory effects of GH and IGF-I with rhFSH were blocked by the administration of leptin (Figs. 1, C and D; 2, C and D; and 3, respectively). The effect of leptin on follicular diameter, E2 secretion, and IR-inhibin secretion by preantral follicles cultured with GH or IGF-I alone or with rhFSH is shown in Figure 3. Because follicles showed a linear increase in size during 4 days of culture, results on Day 4 only were presented. As shown in the left panel, IGF-I did not increase follicular diameter, E2, or IR-inhibin secretion by follicles obtained from immature mice, and the administration of leptin from doses of 1 to 1000 ng/ml did not cause any effect on follicular size. However, IGF-I showed a significant increase in follicular diameter, E2 secretion, and IR-inhibin secretion when cultured with rhFSH. This combined effect of IGF-I and rhFSH, however, was significantly inhibited in a dose-related manner as a result of the addition of leptin. As shown in the right panel of Figure 3, GH alone significantly increased follicular diameter, E2 secretion, and IR-inhibin secretion, and the administration of leptin from doses of 1–1000 ng/ml did not cause any effect on follicular diameter, E2 secretion or IR-inhibin secretion. Administration of FSH further increased the effect of GH, and the effect of GH and rhFSH on follicular growth was significantly inhibited by the administration of leptin. These results indicate that leptin has an inhibitory action on preantral follicles cultured in the presence of FSH. As shown in Figure 3, preantral follicles from immature mice do not respond to FSH, we did not examine whether leptin modulates the effect of FSH on preantral follicles from immature mice.



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  		FIG. 1. Morphological changes in preantral follicles from immature mice cultured for 4 days in the presence of medium alone (A), rhFSH (100 mIU/ml) + IGF-I (100 ng/ml) (B), and rhFSH + IGF-I + leptin (30 ng/ml) (C). Magnification x200. Changes in the number of granulosa cells of each group were shown in D. **P < 0.0001; *P < 0.001. ( ), Number of follicles examined



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  		FIG. 3. Changes in follicular diameter of preantral follicles and E2 and IR-inhibin secretion from follicles of immature mice cultured for 4 days with each of rhFSH (100 mIU/ml), IGF-I (100 ng/ml), GH (1 mIU/ml), and combined with doses of 1, 10, 30, 100, and 1000 ng/ml leptin. Experiments were repeated five to eight times for each reagent. The data shown are the mean and SEM. a, P < 0.0001; b, P < 0.001; c, P < 0.01; d, P < 0.05 versus FSH + GH + zero leptin; e, P < 0.0001; f, P < 0.01 versus control; g, P < 0.0001 versus FSH alone

Figure 4 shows the effect of leptin on follicular growth of preantral follicles from adult mice, cultured in the presence of FSH alone. Preantral follicles from adult mice showed a significant increase in diameter as a result of stimulation by 100 mIU/ml of rhFSH. As seen in the figure, leptin at doses of 10 ng/ml and 100 ng/ml significantly inhibited the effect of FSH, suggesting that leptin blocked the stimulatory effect of FSH on preantral follicular growth. As shown in Figure 5, leptin inhibited the preantral follicular growth of adult mice in a dose-related manner, and even a dose of 1 ng/ml of leptin resulted in a significant suppression of IR-inhibin and E2 secretion. Figure 6 show the morphological appearance of a preantral follicle cultured for 4 days with FSH alone and with 100 ng/ml of leptin, respectively. Administration of FSH significantly increased follicular diameter and the number of granulosa cells, but the stimulatory effect of FSH on preantral follicles was significantly blocked by administration of leptin.



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  		FIG. 4. Changes in the diameter of preantral follicles from adult mice. Preantral follicles were cultured for 4 days with the medium alone (control), rhFSH (100 mIU/ml), rhFSH plus 10 ng/ml leptin, and rhFSH plus 100 ng/ml leptin. Follicular growth was checked daily, and degenerated follicles were removed. Experiments were repeated five to eight times for each reagent. The data shown are the mean and SEM. a, P < 0.0001; b, P < 0.001



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  		FIG. 5. Changes in follicular diameter of small preantral follicles and E2 and IR-inhibin secretion from follicles obtained from adult mice (8 wk old) cultured with each of rhFSH and a combination of the doses of 1, 10, 30, 100, and 1000 ng/ml leptin (ng/ml). Experiments were repeated five to eight times for each reagent. The date shown are the mean and SEM. a, P < 0.0001; and b, P < 0.001 versus FSH (rhFSH) + zero leptin



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  		FIG. 6. Morphological changes in preantral follicles of immature mice cultured for 4 days in the presence of medium alone (A), rhFSH (100 mIU/ml) (B), and rhFSH + leptin (100 ng/ml). Magnification x200. Changes in the number of granulosa cells of each group were shown in D. **P < 0.0001; *P < 0.001. ( ), Number of follicles examined

In order to study the effect of cAMP on follicular growth and the effect of leptin on cAMP and in turn follicular growth, preantral follicles from immature and adult mice were cultured in the presence of 8-Br-cAMP and forskolin for 4 days. The dose of 8-Br-cAMP and forskolin was determined to be 2.5 mM and 0.1 M, respectively, for immature mice and 2.5 mM and 100 M for adult mice, respectively, because the doses of these chemicals showed a maximal response in follicular size and E2 and IR-inhibin secretion (result not shown). Figure 7 shows that 8-Br-cAMP and forskolin caused a significant increase in follicular diameter, E2 secretion, and IR-inhibin secretion of immature mice and adult mice. The stimulatory effects of cAMP and forskolin on follicular growth of the immature mice were significantly inhibited by 100 ng/ml and by the above doses of leptin. However, as shown in Figure 7, up to 1000 ng/ml of leptin had no effect on follicular growth of adult mice.



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  		FIG. 7. Effect of leptin on follicular diameter and E2 and IR-inhibin secretions by small preantral follicles obtained from adult (8 wk old) and immature mice (11 days old) cultured with each of 2.5 mM cAMP (8-bromoadenosine 3:5-cyclic monophosphate) (left panel) and forskolin (right panel) at a dose of 100 M (for adult mice) or 0.1 M (for immature mice). Leptin at doses of 1, 10, 100, and 1000 ng/ml was added as indicated. Experiments were repeated five times for each reagent. The data shown are the mean and SEM. a, P < 0.0001; b, P < 0.001; c, P < 0.01; d, P < 0.05 versus cAMP/forskolin + zero leptin

DISCUSSION

Previous reports [26–29] have shown that leptin has stimulatory effects on reproductive function. This effect of leptin is postulated to be caused by a stimulatory action of leptin on gonadotropin secretion [27]. However, it has been shown that granulosa cells, theca cells, interstitial cells, and cumulus oophorous cells have a specific receptor for leptin [12, 13], and leptin elicits an inhibitory effect on ovarian function [13–16]. Zachow and Magoffin [14] have shown that leptin impaired E2 production by rat granulosa cells cultured in the presence of IGF-I and FSH, while Agarwal et al. [13] have shown a similar effect of leptin on human granulosa and theca cells. In addition, Brannian et al. [30] have shown that leptin inhibits gonadotropin- and insulin-stimulated progesterone production by granulosa cells. Although these studies demonstrated that leptin directly inhibits the activity of E2 secretion after differentiation of granulosa cells, they did not clarify how leptin suppresses the production of ovarian steroids in the cells. Moreover, it was unknown if leptin suppressed the proliferation of granulosa cells. Our present study demonstrated not only that leptin inhibited proliferation of granulosa cells, but also that the inhibitory action of leptin on follicular growth is FSH dependent because the inhibitory action of leptin on follicular growth was seen only when these follicles were cultured in the presence of FSH. In addition, our present study using preantral follicles from adult mice clearly demonstrated that leptin also suppresses the effect of FSH on the early follicular growth of adult mice.

FSH stimulates steroidogenesis in granulosa cells to allow cellular differentiation and development of the follicle. Interaction with a receptor has long been recognized as stimulating an increase in cAMP levels in granulosa cells [31], and cAMP antagonists have been shown to inhibit the effect of FSH on progesterone secretion [32]. Therefore we first examined the effect of cAMP on follicular growth in terms of steroidogenesis and morphological changes. As shown in Figure 7, 8-Br-cAMP and forskolin induced E2 and IR-inhibin secretion as well as an increase in follicular diameter, suggesting that our system can be used to evaluate the effect of cAMP on follicular development. Although preantral follicles from immature mice do not increase their follicular size or E2 or IR-inhibin secretion as a result of stimulation by FSH alone [22], they were able to increase follicular size as well as hormonal secretion as a result of stimulation by cAMP and FSH in conjunction with GH or IGF-I. These results suggest that preantral follicles from immature mice have an intact protein kinase A.

With regard to mechanisms for leptin inhibition of steroidogenesis of granulosa cells, Barkan et al. [33] found that leptin modulates the glucocorticoid- and forskolin-induced ovarian steroidogenesis and proposed one potential hypothesis that leptin attenuates transcriptional activities of genes by overexpressing c-Jun. As shown in Figure 7, leptin suppressed cAMP-induced folliculogenesis of preantral follicles from immature mice. Because the cAMP system is functioning in these follicles, it is suggested that leptin may block events downstream to the cAMP-dependent signal transduction pathway. However, thus far we do not have direct evidence as to whether the cAMP-dependent signal transduction pathway has cross-talk with c-Jun. On the other hand, leptin did not suppress cAMP-induced follicular growth in adult mice. Nevertheless, leptin suppressed FSH-induced follicular growth of adult mice, suggesting that the inhibitory mechanisms of leptin on the action of FSH are independent of a cAMP protein kinase pathway in adult mice. It has been shown that besides a cAMP protein kinase A pathway, there are several signal transduction mechanisms in the ovary. One of the examples is the phospholipase C pathway, and it has been shown that activation of this pathway suppresses the FSH-induced progesterone synthesis in rat granulosa cells [34]. Thus, the differing inhibitory action of leptin on follicular growth in immature and adult mice can be accounted for by the presence of multiple signal transduction systems in adult mice. However, the precise mechanisms and how they are controlled as well as why preantral follicles from adult mice need to acquire such transformation still remain unclear.

It is said that both IGF-I and GH synergized with FSH in the stimulation of cAMP accumulation [35]. Nevertheless, leptin suppressed follicular growth stimulated by IGF-I + FSH and GH + FSH, but follicular growth stimulated by GH alone was not affected (Fig. 3). Moreover, leptin did not suppress follicular growth stimulated by GH + FSH to the level of the control. Thus, the present results suggest that an inhibitory action of leptin is manifested by reduction in FSH-dependent follicular growth, but the mechanisms and physiological significance of such a specific inhibition are unknown.



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  		FIG. 2. Morphological changes in preantral follicles of immature mice cultured for 4 days in the presence of medium alone (A), rhFSH (100 mIU/ml) + GH (1 mIU/ml) (B), and rhFSH + GH + leptin (30 ng/ml) (C). Magnification x200. Changes in the number of granulosa cells of each group were shown in D. **P < 0.0001; *P < 0.001. ( ), Number of follicles examined

ACKNOWLEDGMENTS

We thank Miss Y. Hayashi and Miss T. Ishihara for their assistance.

FOOTNOTES

First decision: 12 December 2000.

1 Correspondence: Hideki Mizunuma, Department of Obstetrics & Gynecology, Gunma University School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan. FAX: 81 27 220 8443; mizunuma{at}med.gunma-u.ac.jp Back

Accepted: February 9, 2001.

Received: November 3, 2000.

REFERENCES

  1. Zhang Y, Proenca R, Maffei M, Barone M, Leopold L, Friedman JM. Positional cloning of the mouse obese gene and its human homologue. Nature 1995; 372:425-432
  2. Halaas JL, Gajiwala KS, Maffei M, Cohen SL, Chait BT, Rabinowitz D, Lallone RL, Burley SK, Friedman JM. Weight-reducing effects of the plasma protein encoded by the obese. Science 1995; 269:543-546[Abstract/Free Full Text]
  3. Considine RV, Sinha MK, Heiman ML, Kriauciunas A, Stephens TW, Nyce MR, Ohannesian JP, Marco CC, McKee LJ, Bauer TL. Serum immunoreactive-leptin concentrations in normal-weight and obese humans. N Engl J Med 1996; 334:292-295[Abstract/Free Full Text]
  4. Campfield LA, Smith FJ, Guisez Y, Devos R, Burn P. Recombinant mouse OB protein: evidence for a peripheral signal linking adiposity and central neural networks. Science 1995; 269:546-549[Abstract/Free Full Text]
  5. Maffei R, Halaas J, Friedman JF. Leptin levels in human and rodent: measurement of plasma leptin and ob RNA in obese and weight-reduced subjects. Nat Med 1995; 1:1155-1161[CrossRef][Medline]
  6. Pelleymounter MA, Cullen MJ, Baker MB, Hecht R, Winters D, Boone T, Collins F. Effects of the obese gene product on body weight regulation in ob/ob mice [see comments]. Science 1995; 269:540-543[Abstract/Free Full Text]
  7. Weigle DS, Bukowski TR, Foster DC, Holderman S, Kramer JM, Lasser G, Lofton-Day CE, Prunkard DE, Raymond C, Kuijper JL. Recombinant ob protein reduces feeding and body weight in the ob/ob mouse. J Clin Invest 1995; 96:2065-2070
  8. Barash IA, Cheung CC, Weigle DS, Ren H, Kabigting EB, Kuijper JL, Clifton DK, Steiner RA. Leptin is metabolic signal to the reproductive system. Endocrinology 1996; 137:3144-3147[Abstract]
  9. Chehab FF, Lim ME, Lu R. Correction of the sterility defect in homozygous obese female mice by treatment with the human leptin. Nat Genet 1996; 12:318-320[CrossRef][Medline]
  10. Cioffi JA, Shafer AW, Zupancic TJ, Smith-Gbur J, Mikhail A, Platika D, Snodgrass HR. Novel B219.OB receptor isoforms: possible role of leptin in hematopoiesis and reproduction. Nat Med 1996; 2:585-589[CrossRef][Medline]
  11. Karlsson C, Lindell K, Svensson E, Bergh C, Lind P, Billig H, Carlsson LM, Carlsson B. Expression of functional leptin receptors in the human ovary. J Clin Endocrinol Metab 1997; 82:4144-4148[Abstract/Free Full Text]
  12. Zachow RJ, Weitsman SR, Magoffin DA. Leptin impairs the synergistic stimulation by transforming growth factor-beta of follicle-stimulating hormone-dependent aromatase activity and messenger ribonucleic acid expression in rat ovarian granulosa cells. Biol Reprod 1999; 61:1104-1109[Abstract/Free Full Text]
  13. Agarwal SK, Vogel K, Weitsman SR, Magoffin DA. Leptin antagonizes the insulin-like growth factor-I augmentation of steroidogenesis in granulosa and theca cells of the human ovary. J Clin Endocrinol Metab 1999; 84:1072-1076[Abstract/Free Full Text]
  14. Zachow RJ, Magoffin DA. Direct intraovarian effects of leptin: impairment of the synergistic action of insulin-like growth factor-1 on follicle-stimulating hormone-dependent E2-17 production by rat ovarian granulosa cells. Endocrinology 1997; 138:847-850[Abstract/Free Full Text]
  15. Spicer LJ, Francisco CC. Adipose obese gene product, leptin, inhibits bovine ovarian thecal cell steroidogenesis. Biol Reprod 1998; 58:207-212[Abstract/Free Full Text]
  16. Spicer LJ, Francisco CC. The adipose obese gene product, leptin: evidence of a direct inhibitory role in ovarian function. Endocrinology 1997; 138:3374-3379[Abstract/Free Full Text]
  17. Jacobs HS, Conway GS. Leptin, polycystic ovaries and polycystic ovary syndrome. Hum Reprod Update 1999; 5:166-171[Abstract/Free Full Text]
  18. Brzechffa PR, Jakimiuk AJ, Agarwal SK, Weitsman SR, Buyalos RP, Magoffin DA. Serum immunoreactive leptin concentrations in women with polycystic ovary syndrome. J Clin Endocrinol Metab 1996; 81:4166-4169[Abstract/Free Full Text]
  19. Harlass FE, Plymate SR, Fariss BL, Belts RP. Weight loss is associated with correction of gonadotropin and sex steroid abnormalities in the obese anovulatory female. Fertil Steril 1984; 42:649-652[Medline]
  20. Agarwal SK, Judd HL, Magoffin DA. A mechanism for the suppression of estrogen production in polycystic ovary syndrome. J Clin Endocrinol Metab 1996; 81:3686-3691[Abstract]
  21. Butzow TL, Moilanen JM, Lehtovirta M, Tuomi T, Hovatta O, Siegberg R, Nilsson CG, Apter D. Serum and follicular fluid leptin during in vitro fertilization: relationship among leptin increase, body fat mass, and reduced ovarian response. J Clin Endocrinol Metab 1999; 84:3135-3139[Abstract/Free Full Text]
  22. Yokota H, Yamada K, Liu X, Kobayashi J, Abe Y, Mizunuma H, Ibuki Y. Paradoxical action of activin a on folliculogenesis in immature and adult mice. Endocrinology 1997; 138:4572-4576[Abstract/Free Full Text]
  23. Liu X, Andoh K, Yokota H, Kobayashi J, Abe Y, Yamada K, Mizunuma H, Ibuki Y. Effect of growth hormone, activin, and follistatin on the development of preantral follicle from immature female mice. Endocrinology 1998; 139:2342-2347[Abstract/Free Full Text]
  24. Hamada T, Watanabe G, Kokuho T, Taya K, Sasamoto S, Hasegawa Y, Miyamoto K, Igarashi M. Radioimmunoassay of inhibin in various mammals. J Endocrinol 1989; 122:697-704[Abstract]
  25. Crowley WF Jr, Beitins IZ, Vale W, Kliman B, Rivier J, Rivier C, McArthur JW. The biologic activity of a potent analogue of gonadotropin-releasing hormone in normal and hypogonadotropic men. N Engl J Med 1980; 302:1052-1057[Abstract]
  26. Cunningham MJ, Clifton DK, Steiner RA. Leptin's actions on the reproductive axis: perspectives and mechanisms. Biol Reprod 1999; 60:216-222[Abstract/Free Full Text]
  27. Ahima RS, Dushay J, Flier SN, Prabakaran D, Flier JS. Leptin accelerates the onset of puberty in normal female mice. J Clin Endocrinol Metab 1997; 99:391-395
  28. Cheung CC, Thornton JE, Kuijper JL, Weigle DS, Clifton DK, Steiner RA. Leptin is a metabolic gate for the onset of puberty in the female rat. Endocrinology 1997; 138:855-858[Abstract/Free Full Text]
  29. Chehab FF, Mounzih K, Lu R, Lim ME. Early onset of reproductive function in normal female mice treated with leptin. Science 1997; 275:88[Abstract/Free Full Text]
  30. Brannian JD, Zhao Y, McElroy M. Leptin inhibits gonadotrophin-stimulated granulosa cell progesterone production by antagonizing insulin action. Hum Reprod 1999; 14:1445-1448[Abstract/Free Full Text]
  31. Erickson GF, Ryan KJ. The effect of LH/FSH, dibutyryl cyclic AMP, and prostaglandins on the production of estrogens by rabbit granulosa cells in vitro. Endocrinology 1975; 97:108-113[Abstract]
  32. Adashi EY, Resnick CE, Jastorff B. Blockade of granulosa cell differentiation by an antagonistic analog of adenosine 3',5'-cyclic monophosphate (cAMP): central but non-exclusive intermediary role of cAMP in follicle-stimulating hormone action. Mol Cell Endocrinol 1990; 72:1-11[CrossRef][Medline]
  33. Barkan D, Jia H, Dantes A, Vardimon L, Amsterdam A, Rubinstein M. Leptin modulates the glucocorticoid-induced ovarian steroidogenesis. Endocrinology 1999; 140:1731-1738[Abstract/Free Full Text]
  34. Hsueh AJ, Adashi EY, Jones PB, Welsh TH Jr. Hormonal regulation of the differentiation of cultured ovarian granulosa cells. Endocr Rev 1984; 5:76-127[Medline]
  35. Adashi EY, Resnick CE, Hernandez ER, May JV, Knecht M, Svoboda ME, Van-Wyk JJ. Insulin-like growth factor-I as an amplifier of follicle-stimulating hormone action: studies on mechanism(s) and site(s) of action in cultured rat granulosa cells. Endocrinology 1988; 122:1583-1591[Abstract]



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